Communication in broadband wireless networks is generally divided between access and backhaul. A radio access network (known as RAN) is the air interface network providing traffic communication between mobile terminals (subscribers) and their associated access points (base stations), while a backhaul network is the air interface network providing traffic communication between the various base stations and a core network. The networks may be arranged to transfer data alone, or may be arranged for triple play services (video, audio and data). In conventional systems, the access network and the backhaul network each require their own separate transmission equipment, antennas, etc., at great cost to the operator. These Radio Access Networks (RAN) use an out-of-band backhauling method, where access and backhauling networks communicate over separate and widely separated frequency bands, thus wasting the important resource of spectrum.
One example of a conventional backhaul network involves connecting wireless base stations to corresponding core mobile networks (such as ASN GateWay, AAA servers, etc). The choice of backhaul technology must take into account such parameters as capacity, cost and coverage. Base station backhaul typically is performed via wired infrastructure (e.g., E1/T1 leased lines), or via wireless Point-to-point (PTP) microwave links to each base station, which is expensive to deploy, in terms of equipment and installation. In particular, due to the direct, uninterrupted line-of-sight requirements of the wireless backhaul equipment, in high frequency bands such as 6 GHz-36 GHz, the backhaul components of conventional base stations require strategic deployment at high locations on tall and expensive towers.
There are also known outdoor Wi-Fi (a registered trademark) networks, deployed mainly according to outdoor Wi-Fi mesh technology. In the micro/pico-cell deployment approach of conventional Wi-Fi mesh networks, due to multiple access point nodes in the network, backhauling becomes more complicated and costly. Backhauling each node via wired lines (E1/T1 or DSL) is impractical in a dense deployment of nodes. On the other hand, backhauling each node via traditional wireless PTP microwave links is expensive due to costly equipment and installation costs and deployment is not feasible on telephone poles, street poles, electricity poles, etc. In Wi-Fi, like in WiMAX (a registered trademark), PTP microwave links require high deployment to achieve a clear line-of-sight between nodes. In addition, when the network load increases, the backhaul network losses drastically degrade the overall network performance (by limiting capacity and increasing latency).
There is known from applicants' co-pending US patent application publication no. US 2008/0090575, entitled WiMAX Access Point Network with Backhaul Technology, a mobile wireless broadband communication network, as defined in IEEE Standard 802.16e-2005 Standardization for WiMAX. According to this application, there is provided in-band, point-to-point backhaul between the various access network elements in a wireless broadband network deployed in micro- or pico-cells. This wireless broadband communication network provides increased traffic capacity of the base station, while not greatly increasing the interference caused with neighboring cells, preferably by using several directional antennae on each base station, and utilizing MIMO or beam forming (spatial filtering) techniques to reduce interference. The backhaul system and method is described in greater detail in Applicant's co-pending US patent publication no. 2008/0049672, entitled Point-to-Point Backhaul with Interference Mitigation, with regard to applicants' wireless broadband, particularly WiMAX, networks. However, other wireless technologies, such as 3GPP-LTE, 3G, 3G-HSDPA, HSUPA, GSM and other cellular technologies, as conventionally implemented, have separate out-of-band backhaul networks and do not have the capability of such in-band backhaul between access points.
Consequently, there is a need for an in-band backhaul method that can be implemented in any of a variety of wireless telecommunication and cellular technologies.